body {
    margin: 20px;
    padding: 0;
    background: #333;
}

.container {
    max-width: 760px;
    margin: auto;
    border: #fff solid 3px;
    background: #fff;
}

.main-img img,
.imgs img {
    width: 100%;
}

.imgs {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-gap: 5px;
}


/* fade in */

@keyframes fadeIn {
    to {
        opacity: 1;
    }
}

.fade-in {
    opacity: 0;
    animation: fadeIn 0.5s ease-in 1 forwards;
}